Cape Town - South Africa criticised Royal Dutch Shell's local unit on Tuesday for not refuelling a jet carrying the visiting speaker of Iran's parliament, saying the action was an "embarrassment" to the government.
Ali Larijani met with President Jacob Zuma and South Africa's parliamentary speaker during an official visit to the country from March 4 to 7.
But Larijani was forced to cancel the next leg of a planned African tour because of a 24-hour delay when his plane was not refuelled at Cape Town International Airport.
The South African Petroleum Industry Association (Sapia), which groups suppliers such as Shell, said this was because of "company-specific global policies" its members follow in dealing with Iran, which has had international sanctions imposed on it over its nuclear programme.
"In accordance with these company restrictions, the relevant Sapia members were not able to sell fuel or provide refuelling services to Dr Larijani's aircraft prior to its departure from Cape Town on March 7 2014," Sapia said in a statement.
Iran agreed under an interim deal with world powers in November to curb sensitive nuclear activities in return for limited sanctions relief.
The South African government said it did not think sanctions applied in this situation.
"The department regretted the embarrassment that had been caused to the government of South Africa and to its guest by a unilateral decision by Shell SA not to refuel Dr Larijani's aircraft," the foreign affairs department said in a statement.
"The decision, ostensibly due to unilateral sanctions that had been imposed against Iran, was not based on fact. Despite assurances provided to the company by the department and by the Ambassador of the European Union to South Africa, Shell refused all requests to refuel the aircraft," it said.
South Africa called on Shell to act in a manner appropriate "to its contractual role" as a service provider appointed by an agency of government to provide fuel to aircraft at national airports.
Shell SA did not respond directly to requests for comment, but referred queries to Sapia.